Internal combustion engines are often equipped with balancing shafts systems adapted to compensate varying loads on crankshafts. As balancing shafts have eccentric balancing masses which generate heavy loads, the rotation of balancing shafts is allowed by rolling bearings mounted in supports of the internal combustion engine.
A balancing shaft can be driven by a gear. It is particularly well known to provide a scissors gear to balancing shaft so as to prevent backlash between driving and following gears due to rotational speed variations.
The scissors gear generally comprises a main gear, an auxiliary gear, and a scissors spring housed in a cavity defined between the main and auxiliary gears, so as to lessen the amount of backlash.
Scissors gear is supported by a rolling bearing, the main gear being press-fitted onto an outer cylindrical surface of an outer massive ring of the rolling bearing while the auxiliary gear is mounted with a loose-fit onto the cylindrical surface. An inner ring of the rolling bearing is mounted onto a portion of the balancing shaft.
Basically, the outer ring comprises an axial blocking flange to maintain axially the auxiliary gear. However, a massive ring provided with such cylindrical surface and flange means a grinding process on the outer ring diameter to optimize the mounting process. Moreover, such massive ring is relatively expensive.